This invention relates to a pivoting vane design for a rotary compressor and in particular to a pivoting vane for a rotary compressor of the type used in oxygen concentrators and other analogous applications.
Conventional oxygen concentrators often employ a rotary compressor to pump air through the concentrator and to the patient. Such compressors provide a desirably high rate of air flow and do not generate excessive pressures. The typical rotary compressor features carbon vanes that are slidably mounted in generally radial slots in the compressor""s rotor. The rotor itself is eccentrically mounted in a chamber formed in the housing of the compressor. An electric motor drives the rotor such that centrifugal force urges the carbon vanes outwardly from their slots to engage the wall of the chamber. The vanes form successive compartments that collect air that is introduced into the compressor. As the vanes rotate, the air is moved into a gradually constricted portion of the chamber where it is compressed. This compressed air is then delivered through an exhaust port to the concentrator""s filter.
Conventional carbon vane rotary compressors exhibit at least a couple of significant problems. As each vane slides back and forth within its respective slot, a considerable amount of heat is generated. Moreover, the friction resulting from such sliding causes the vanes to wear and generates carbon dust, which can foul the compressor. As a result, these types of compressors required frequent maintenance. In particular, the dust must be removed an the vanes replaced at regular intervals. Moreover, due to the constant wear on the vanes, known rotary compressors are very likely to exhibit gaps between the ends or tips of the vanes and the chamber wall. This can result in air leakage, which may significantly impair the operation of the compressor and the oxygen concentrator.
Compressors have been provided to overcome the foregoing difficulties. See my U.S. Pat. No. 5,188,524. That device employs a pivoting vane rotary compressor wherein pairs of opposing vanes mounted to a rotor define pockets or compartments. As the vane rotate, the respective compartments are gradually constricted to compress the air or oxygen being transmitted by the machine. Although this product works quite well, I have determined that it is desirable to further reduce the space of the compartments so that improved compression and efficiency are achieved.
It is therefore an object of this invention to provide an improved pivoting vane rotary compressor that achieves significantly improved compression and efficiency.
It is a further object of this invention to provide a pivoting vane rotary compressor that is much more durable and effective and is far less likely to exhibit maintenance problems than conventional sliding carbon vane compressors.
This invention features a rotary compressor including a housing having a generally cylindrical chamber. There is a rotor mounted eccentrically in the chamber to define about the rotor a main chamber region, which narrows to a constricted chamber region. The rotor includes a circumferential surface. An intake port is formed in the housing for introducing air into the main chamber region. An exhaust port is formed in the housing for discharging air from the constricted chamber region. There is at least one pair of curved vanes pivotably and circumferentially attached to the rotor and extending in generally opposite arcuate directions from the rotor into the chamber. There are means for rotatably driving the rotor in a single direction such that the pair of vanes are urged against the wall of the chamber to define a compartment that transmits air from the main chamber region to the constricted chamber region. This transmitted air is compressed and discharged to the exhaust port. Each vane has a curvature that substantially conforms to the circumferential curvature of the rotor. As a result, each vane is urged into substantially flush interengagement with the circumferential surface of the rotor when the vane is driven by the rotor into the constricted chamber region. This shrinks the volume of the compartments within the constricted region to increase the air compression therein.
In a preferred embodiment, each pivoting vane includes an arcuate portion and an enlarged or thickened distal end portion. The rotor may include at least a pair of circumferential recesses. Each such pair of recesses receives a corresponding pair of pivoting vanes when that pair of vanes is driven by the rotor into the constricted chamber region. This further reduces the size of the compartment defined by the pair of vanes and increases the air pressure within that compartment. The recesses may be positioned on the rotor to receive the enlarged distal end portions of the pivoting vanes. Typically, each recess is associated with and receives a first pivoting vane from one pair of vanes and a second, oppositely extending pivoting vane from a second, adjacent pair of vanes. In other words, each recess accommodates one pivoting vane from each of two adjacent pairs of vanes. At least one adjoining pair of vanes may extend convergently relative to one another and at least one pair may extend divergently relative to one another.
In alternative embodiments, the entire pivoting vane may fit in a respective recess. In still other versions, recesses may be omitted and the vanes may flushly interengage the outer surface of the rotor.